In a multicast environment, such as a multicast virtual private network (MVPN), protocol independent multicast (PIM) may be executed over a virtual local area network (LAN), such as a multicast distribution tree or “MDT,” that connects all the provider edge devices (PEs) participating in the multicast environment. The number of devices that participate in PIM is generally equal to the number of PEs that are enabled for multicast in that multicast environment, which in large multicast deployments may reach 1000 PEs per VPN.
PIM typically executes over a virtual LANs such that each device/node enabled for PIM sends out periodic PIM “Hello” messages to announce itself as multicast capable, often including a listing of supported attributes. If, for example, an MVPN has 1000 multicast enabled devices (e.g., PEs), each device will generally have a PIM neighbor list of 999 entries. Since PIM Hello messages may be transmitted by each device once every thirty seconds, the PIM neighbor list is refreshed by receiving approximately 33 Hello messages per second (999 entries/30 seconds). Notably, in the event a PIM device is connected to multiple large MVPNs, this load is going to be even higher. While this may not be a concern for systems capable of handling the instances of such large multicast deployments with high numbers of PEs (which are rare in today's networks), scalability of PIM may still remain a concern for certain customers.